State-of-charge estimation for lithium-ion batteries based on incommensurate fractional-order observer

Abstract

This paper presents a new state-of-charge (SOC) estimation method for lithium-ion batteries (LIBs) based on incommensurate fractional-order (FO) observer. First, a FO RC equivalent circuit model is constructed to describe the charging and discharging dynamic characteristics of the LIB. An adaptive FO particle swarm optimization (AFOPSO) algorithm is employed to identify the parameters of the established FO model. The accuracy of the parameterized model is verified, showing its superiority over the available ones. Then, by using the comparison principle of FO systems with multi-order and stability of FO incommensurate linear systems with multi-order, a new order-dependent incommensurate FO observer is designed for battery SOC estimation. Finally, the validity and feasibility of the proposed SOC observer are examined with real time experimental data of LIBs.